1. Field of the Invention
The present invention relates to an apparatus and method for releasing tension members for use in an anchor method to provide soft ground reinforcement for civil engineering projects, and more particularly, to an apparatus and method for releasing tension members for use in an anchor method, in which both ends of the tension member are firmly and stably held by anchors, where all or some of the wires are cut, and at least one end of the cut wires is hit to release the tension member.
2. Description of Related Art
Generally, an anchor method is used to reinforce soft ground by drilling a hole into the ground, inserting an anchor member composed of a grout-feeding hose and a tension member into the drilled hole, pouring grout into the anchor member through the grout-feeding hose, curing the grout with the anchor member, fastening an anchor with one end of the tension member, and drawing the tension member by use of tensioning equipment to apply tension to the grout and the ground. Such an anchor method is mainly used for land-side protection wall construction, stone setting works, retaining wall construction, etc.
The application of the anchor method offers advantages of increased effectiveness in managing downtown construction, reduction in the required duration of projects, etc. Upon carrying out further construction in an adjacent region, drilling and boring machinery is required and the duration of projects is lengthened due to the embedding of tension members with strength six times stronger than that of common steel reinforcements. In order to solve the above problem, an anchor for removing the tension member after the completion of the drilling construction has been developed, and it is referred to as a tension member-releasing apparatus for use in an anchor method.
Several tension member-releasing apparatuses for use in the anchor method have been proposed. For example, one tension member-releasing apparatus for use in an anchor method is disclosed in Korean Utility Model Publication No. 20-0242474. In this Utility Model, the apparatus includes a body formed with a threaded portion for fastening a cap on an outer surface of an upper end thereof and which has a wedge-receiving space; a wedge assembly mounted in the wedge-receiving space of the body, which has an external ring mounted on a groove formed on the outer surface of the wedge assembly for maintaining an assembled state thereof and which is radially expanded by an internal ring mounted on an inner groove, and in which a spoiler is inserted into a spoiler groove formed at a front portion of the inner groove; a locking member for seating the spoiler containing a resilient hook to the spoiler groove of the wedge assembly; and the cap having a protrusion which is fastened to the upper portion of the body and receives a resilient hook.
According to the method for releasing the tension member by use of the tension member-releasing apparatus described above, if the tension member installed in the ground in a tensioning state is cut, then the tension member is moved toward the embedded anchor by means of repulsive force resulting from the release of tension in the tension member. At that time, the tension member and the wedge assembly mounted to the end of the tension member are moved into the wedges, and thus the wedges are expanded, thereby allowing the front end of the tension member to be released from the wedges.
The locking member assembled to the wedge assembly is also moved together with the tension member, and the resilient hook of the locking member is inserted and fixed to the protrusion of the cap. After the resilient hook of the locking member is fixed to the protrusion of the cap, all wedges of the wedge assembly are expanded to release the locking of the tension member. Therefore, the tension member may be drawn by pulling the tension member.
If the tension member is not released due to a weak repulsive force, the cut end of the tension member is hit by a hammer so that the tension member is moved toward the anchor, thereby causing the resilient hook of the locking member to abut against the protrusion.
According to the conventional tension member-releasing apparatus disclosed in the publication, if external shock is applied to the wedge assembly with the tension assembled thereto due to carelessness, necessity or some other reason, the tension member is inserted and thus the resilient hook of the locking member mounted on the upper end of the wedge assembly is locked by the protrusion of the cap. When this occurs, it is impossible to release the tension member from the wedge assembly. Therefore, a problem results in that the wedge assembly may not be reused because all wedges of the wedge assembly have become expanded.
In addition, a significant amount of force is required to hit the tension member so that the resilient hook of the locking member will become abutted against the protrusion of the cap. Also, another potential problem exists in that the hammer can miss the tension member due to carelessness.